Surface Modification of Al₂O₃–ZrO₂(Y₂O₃) Eutectic Oxides by Laser Melting: Processing and Wear Resistance

Abstract

) eutectic oxides were produced by laser melting of the surface of conventionally sintered materials using a high-power diode laser. It was possible to obtain smooth, homogeneous, and crack-free coatings up to 50 Â 7 mm 2 in area by carefully controlling the processing conditions (laser power, traveling speed of the specimen, and substrate temperature). The surface treatment was aimed at creating a dense, wear-resistant coating based on the eutectic microstructure generated upon solidification. The microstructure of the coating was formed by elongated colonies, and was similar to that found in rods grown by the laser-heated floating zone method at the same growth rates. The laser-melted coating presented much higher hardness and wear resistance than the sintered materials, and the optimum mechanical properties were measured in samples treated at 500 mm/h with a laser line power of 65-80 W/cm. These samples presented a hardness and wear rate of 19.770.4 GPa and 3.8 Â 10 À6 mm 3 /N m, respectively, while those of the conventionally sintered materials were 14.37 0.2 GPa and 2.3 Â 10 À6 mm 3 /N m.

Laser-assisted, crack-free surface melting of large eutectic ceramic bodies

“…Laser melting and resolidification of ceramic surfaces has been used in the past with the objective of sealing porous ceramic refractories [14], changing the wettability of the surface [5], increasing wear resistance [6,7], modifying tribology properties [8], repairing of localized manufacturing defects [9], texturing the surface layer [10], producing functional coatings on ceramics [11], or modifying the pore architecture and thermophysical properties of thermal barrier coatings applying a combined plasma spraying with insitu laser remelting process [12,13] etc. It is difficult, however, to completely suppress crack development during processing, because of the large thermal gradients that the brittle material is subjected to during extremely localized heating by the laser beam.…”

Characterization and modification of technical ceramics through laser surface engineering

“…To date, limited investigations have been performed with respect to achieving an ideal surface treatment of various ceramics with due to the ceramic not being crack pore and defect free [38][39][40][41][42][43]. Ester et al [38] conducted an investigation on Al 2 O 3 and ZrO 2 -based oxide ceramics by employing a HPDL.…”

“…Ester et al [38] conducted an investigation on Al 2 O 3 and ZrO 2 -based oxide ceramics by employing a HPDL. A laser irradiated area of 50 mm  7 mm was said to have a crack-free surface.…”

Compositionally graded YSZ–NiO composites by surface laser melting

“…7 Laser melt processing of materials is also a well-known subject among technologist and material scientist working with metals. 8 Its application to ceramics is scarcer [9][10][11] as ceramics tend to be fragile, and special attention has to be paid to handle the processing thermal stresses. The procedure we are interested ଝ Presented at ELECTROCERAMICS XI, A-013-I.…”

“…The procedure we are interested ଝ Presented at ELECTROCERAMICS XI, A-013-I. * in generates a surface dense crystallised eutectic composite on top of a dense 11 or porous 12 eutectic ceramic, with the same or different compositions. 13 Applications of the procedure exist in all areas where dense and smooth thick ceramic covering layers are required: erosion and abrasion resistance, wear resistance, etc.…”